Several electronic systems require analog-to-digital converters (ADCs) for their function. Depending on the characteristics of the system, there are specific requirements to the ADC and the performance parameters of the ADC. Increased performance as accuracy, resolution and linearity comes at a cost of increased power dissipation due to the laws of physics. The electronics industries therefore strive to obtain the best possible performance at the lowest possible power dissipation.
For many systems, the requirement to the ADC is very dependent on external conditions. For example, in a mobile communication system, the requirements vary according to distance to the base station and the presence of interfering signals. The system is therefore designed to work under worst scenarios resulting in higher requirements for the ADC and other circuitry. This results in an average power dissipation that is much higher than required since the requirements are set for worst case scenarios while the system very seldom operates under these conditions.
System designers therefore need ADCs where the accuracy and performance can be modified during operation. Previously, the solutions have been able to scale power dissipation with only a few percent by switching on and off auxiliary blocks and adjusting supply currents in the ADC. These solutions suffer from unpredictable performance in the low performance mode since each block work under unintended condition. The range of power dissipation variation is also very small.